The present invention relates to electric guitars. More particularly, the present invention relates to improved electronics for reducing the noise and other interference products produced by electric guitars.
Electric guitars are popular musical instruments capable of producing a wide range of sounds when used in cooperation with appropriate sound amplification devices. Moreover, the electric guitar typically includes features allowing a musician to produce acoustic response of varying volume and sound quality.
For the most part, electric guitars have changed little over the past few decades. To produce sound, guitars typically have three pickups which are positioned beneath metal strings. The pickups include one or more electrical coils which pick up the vibration of the metal strings, in a magnetic field. The electrical output of the coils is then amplified and the amplified signal is reproduced by means of a loud speaker. Typically, each pickup is composed of a single coil of wire having two ends connectable to a guitar output circuit. The pickup which is mounted nearest the string anchor is capable of picking up mostly the high frequency components of the vibrations of the metal strings. This is due to the fact that the amplitude of the vibration is reduced as the distance from the string anchor decreases. Conversely, the pickup furthest from the string anchor is capable of picking up more of the low frequency components of the string vibrations, while the pickup positioned midway picks up more of the midrange components of the string vibrations.
Since the pickups are better suited for picking up different frequency components of the mechanical vibrations of the metal strings, it is often desirable to select various combinations of the pickups in parallel for producing different musical effects. For this reason, traditional electric guitars are often provided with a five position switch which allows the selection of one of the pickups, or combinations of two adjacent pickups. Moreover, some guitars are constructed with a humbucker which is a dual coil pickup. Guitars having a humbucker pickup often include a second two position switch for placing the guitar into a single or dual humbucker mode.
Present electric guitars typically have additional circuitry for processing the electric signals produced by the pickups. The processing circuitry is used to alter qualities of the sound. For example, various ranges of notes, such as treble or bass, can be emphasized or de-emphasized. Similarly, the volume and phase of the signals can be controlled. In order to allow the guitar user to adjust the processing of the electronic signal, a guitar typically includes various knobs and buttons for controlling the various sound components including treble, bass and volume. Wires extend from the pickups to the various knobs and buttons of the processing circuitry and then ultimately to an output jack typically mounted toward the bottom of the electric guitar.
Relatively recently, guitars have been constructed to include replaceable pickguard assemblies. Pickguard assemblies include a planar structural deck plate having an outline so as to be replaceably mounted upon the face of a guitar under the guitar""s strings. The deck plate is often referred to as a xe2x80x9cpickguardxe2x80x9d. However, so as to avoid confusion herein between reference to a pickguard and pickguard assembly, the pickguard will be referred to herein simply as a deck plate.
The pickguard assembly includes various electronic components attached to the deck plate for producing the sound of the electric guitar including the pickups, five position switches, humbucker switch, and various knobs and buttons for controlling the processing circuitry. The pickguard assembly further includes the wires which connect the pickups, switches and processing circuitry. Furthermore, the pickguard assembly typically includes an output jack mounted to the deck plate. The output jack is also connected by electrical wires to the processing circuitry. Thus, all of the electronic components of the guitar are mounted on a single replaceable structure of the pickguard assembly. Replacement of a failed electronic component, or otherwise desired substitution of an electrical component, can be rapidly effected by replacement of the pickguard assembly.
Unfortunately, all of the aforementioned guitar structures require routing of a significant amount of wiring between components. This wire harness is terribly susceptible to electrical interference caused by electric motors, neon signs, transformers, electrical appliances, and even the human body which can cause noise, hum and other unwanted sounds to be produced by the electric guitar. Even when the wires are shielded, the guitar electronics are not impervious to noise being introduced into the guitar system. Moreover, shielding can produce a small capacitor effect which alters the tone of the guitar and tends to cut off the high end of the sound spectrum. In addition, increased lengths of the wire connections cause increased degradation of the sound produced by the guitar.
There is thus a significant need for an improved guitar construction which improves sound quality and reduces unwanted noise produced by the guitar.
Briefly, and in general terms, the present invention addresses the aforementioned disadvantages by providing an electric guitar having a pickguard assembly incorporating a multi-layered printed circuit board for purposes of eliminating the traditional wire harness of an electric guitar.
The electric guitar, or similar stringed instrument of the present invention, includes a traditionally shaped deck plate. The deck plate is constructed at least partially, or entirely, of a multi-layered printed circuit board provided with predetermined electrical pathways, also known in the art as traces. The printed circuit board may be mounted on a wooden or plastic deck plate of the prior art. However, preferably, the printed circuit board is integrated into the deck plate, or otherwise forms the deck plate.
The deck plate includes at least one hole for mounting a pickup. Preferably, the deck plate includes three holes positioned in a traditional configuration for mounting three pickups, including one or more humbucker pickups if desired. The deck plate may also include one or more additional holes for placement of various audio processing controls such as volume or tone potentiometers. The processing controls are mounted to the back of the deck plate with buttons or rotating shafts of the controls projecting through the deck plate holes for manual manipulation by a user from the front of the deck plate. In addition, the deck plate may include additional holes or slots for placement of switch assemblies for controlling various functions of the electrical guitar, including selection of individual or combinations of pickups for producing desired sound.
The pickguard assembly""s deck plate further includes a plurality of electrical contacts, also often referred to as solder joints, for electrically connecting the various pickups, signal processing components and switches to the printed circuit board. Preferably, the electrical contacts are positioned as close as possible to the electrical components to reduce the chance of noise being introduced into the circuit. Also preferably, any wires which are used to connect the components to the printed circuit board are shielded by shielding connected to a printed circuit board ground plane. Further, preferably, the printed circuit board includes one or more notch filters electrically connected between the pickups and audio processing controls to eliminate signals below 50 or 60 hertz. Inducted noise, typically between 50 or 60 hertz is often introduced into traditional electric guitar constructions by sources near the instrument. Meanwhile, the pickguard assembly of the present invention eliminates this noise as each pickup output signal is sent to a notch filter to eliminate the source of interference of any 50-60 hertz hum.
The output of the filter is then sent to one or more switches which select the pickup, or a combination of pickups, which are intended to drive the guitar""s acoustic output. The output signal of the switches is preferably then sent to a low-noise pre-amplifier which adjusts the signal level produced by one or more pickups to a value suitable to be controlled by the audio processing controls. These controls alter the volume, and frequency response of the guitar""s acoustic response by enhancing or reducing the frequency response in the bass, midrange, and treble portions of the audio spectrum.
The output of the audio processing controls is then sent either to an additional amplifier, to an output jack mounted on the face of the guitar, or to a wireless transmitter integrated into the printed circuit board itself. Numerous guitar wireless transmitters are known to those skilled in the art which enable a link between the guitar and the sound system including system amplifiers and speakers. However, it is preferred that the guitar of the present invention incorporates a transmitter operating in the VHF, UHF or upper band Ghz radio spectrums with either spread spectrum or frequency hopping type of modulation to avoid undesirable interference within the link between the instrument and sound system. Moreover, it is preferred that the printed circuit board include designated electrical contacts for connection to the wireless transmitter and for any power supply which needs to be connected to the wireless transmitter.
To further improve the sound quality of the guitar of the present invention, the deck plate circuit board is preferably constructed to have low inductance values, and capacitance values below 10 picofarads to compensate for the impedance of the pickup combinations. In a preferred embodiment, the printed circuit board includes six electrically conductive layers. From the front of the deck plate to the rear of the deck plate, these layers are identified as follows: 1) ground; 2) pickup signal to audio processing controls; 3) ground; 4) pickup signal to audio processing controls; 5) power; and 6) ground. Moreover, where the guitar includes an on-board integrated synthesizer (described below), preferably, the printed circuit board includes separated analog and digital signal path layers and ground planes to reduce noise by shielding the signal paths of separate guitar modes.
In an additional preferred aspect of the invention, the circuit board assembly incorporates a synthesizer circuit. The onboard synthesizer is connected to the output of the audio processing controls. The synthesizer receives the unaltered analog signal and implements band pass filtering, such as between 50 hertz and 4 kilohertz. The filtered analog signal is then converted to a digital format using an analog-to-digital converter sampling at a frequency of 10 kilohertz or 11.025 kilohertz. The notes produced by the guitar strings are detected using pitch detection algorithm methodology. Notes are then generated in digital format in accordance with Musical Instrument Digital Interface (MIDI), which is a known standard for connecting musical instruments, synthesizers and computers and which provides the capability to translate music into computer data, and vise versa. The notes in digital format are then altered using a program selection which can be determined by those skilled in the art. Preferably, the synthesizer programming includes capabilities for controlling tone generation and pitch generation as well as other parameters such as timbre, volume, dynamics and phase.
In a preferred embodiment, the synthesizer also includes the capabilities for adding additional harmonics into the audio production. Thus, when a fundamental note is detected, the synthesizer produces chords of corresponding harmonics for audio production. Once the digital signal has been altered to produce the desired audio production, the signal is fed to a digital-to-analog-converter (DAC) and is then sent to the guitar""s output jack or wireless transmitter. For example, by integrating the synthesizer into the printed circuit board and passing the digital signal through a pitch detection algorithm analysis to detect notes, the guitar does not require the use of a phantom pickup which is required to convert traditional electric guitars to an electric guitar having a synthesizer.
Advantageously, the pickguard assembly of the present invention provides for significantly reduced noise and distortion. Wireless transmitters and synthesizers can also be integrated into the pickguard assembly. In addition, the incorporation of an integrated synthesizer into the printed circuit board eliminates the need for a dedicated phantom pickup for attachment to an electric guitar. Moreover, the pickguard assembly can be manufactured relatively inexpensively and provide for superior acoustic response compared to electric guitars available today.
Other features and advantages of the present invention will be appreciated by those skilled in the art upon reading the detailed description which follows with reference to the attached drawings.